This invention relates to high speed food processing machines in which a vertical drive shaft supports and drives food processing blades within an upwardly open food containing bowl. The bowl, which is closed by a lid during food processing, is pivoted for pouring its contents. Typically, a powerful motor on the bottom of the bowl rotates the drive shaft, and a mixing baffle blade is supported through the lid for rotation along and around the inside surface of the bowl for removing and returning foodstuffs from the side of the bowl to the vicinity of the food processing blades for further processing. The blades are removable and interchangeable, so that the blade or other tool configurations may be matched to the processing needs at hand. Machines of this type are highly effective in processing foods, and are so fast (many operations being performed in less than a minute), that the actual processing time is but a small part of the total "turn around" time. That is, it usually takes longer to load and unload the machine than to process the food once it is in the machine.
It is sometimes desirable to introduce ingredients into the bowl while the foodstuffs are being processed. Preferably, these ingredients should be distributed uniformly into the main body of the foodstuffs, and there should be no splashing or throwing of material back out of the bowl. For doing this in prior art devices, they have commonly been stopped, the baffle blade and its drive shaft removed, and then the baffle blade drive shaft hole in the lid is used for this purpose. However, this requires stopping the apparatus, removing a possibly messy baffle blade, and then operating the apparatus without the benefit of the baffle blade while the ingredients are being added.